Energization system for electrostatic precipitators



June 15, 1954` R. G. s'rREuBER ENERGIZATION SYSTEM FOR E LEcTRosTATIc PRECIPITAToRs Filed March 1o, 195s 2 Sheets-Sheet l ATTORNEY 2 Sheets-Sheet 2 R. G. STREUBER o to BY /Y/w/ 7 ATTORNEY y June 15, 1954 ENERGIZATION SYSTEM FOR ELECTROSTATIC PRECIPITATORS Filed March l0, 1953 lcting electrodes arerenergized by alternate waves of the 4alternating current source;

has'the advantage that one surface or the'otherf `'of each 'collecting electrode is always energized.

' can be Patented June 15, 1954 uNlTsD STAT www.. e Y

es. Y rarest 'lorries Application March 10, 1953, Serial No. 341;,39

'7 Claims. (Cl. 183-r7l LThs'invention relates to animproved rectiycationand energization system for electrostatic vpreci'pitators, and has for its primary object the ',provis'ionoi an improved system, particularly "f'fo'r'a precipitator employing mechanical rectijcation', of "simple and rugged construction and v'high efficiency of operation. v

In the conventional form of mechanical reci tiri'er for half-wave operation, a motor operemployed may wreck the entire machine My ating at synchronous speed is equipped with two rotors and two stators, each stator consisting of a` n'umber'or" shoes attached Vto insulatingV supports. The one stator which may be considered therectifier carries a number of shoes corre- ",sponding to the number of poles in the rotor,

which is usually four. 'The other stator which in this vcase may be vconsidered a synchronous yswitch is usually equipped with three shoes.

' Under these circumstances, the transformer EMF Y Y must force the current through six rotor tip-tostator shoe gaps in its complete circuit from one transformer terminal to the other, with consequent considerable losses in voltage and power.- s

charge from theelectrodes during this` phase of thefoperation..

The conventional mechanicalv high voltage 'rectier for precipitatcr serviceis relatively low in --cost and. has practically no current limitations asgcompared to ,electronic tube rectiifiersjwllowyfever, Lit ..does., have I,some major disadvantages.

For: example, there isdangerbf breakageof the yjumper wires used `in the rotatingA parts oisuch machines, which at the necessarily highjspeeds conventional practice are necessarily made of insnlatingmaterial, and Aareaccordiunglysubject to 'mechanical or electrical failure which is also v likely .to cause extensive damage-` Since the ro- In accordance with the present invention, a v

systemof rectification and precipitator energiza- ""'tion'is proposed which notA only reduces these M tip-to-stator-shoe losses in a mechanical rec- 'ti'fier very greatly, butv which also'provides for a very much simplified apparatus, both mechaniv vcally and electrically, and removes nearly all "sources of mechanical and electrical failure which-- experience has proven to aiect adversely bothl` i In the usual application yof half-wave energization, power is applied during one-half of the safety and economy of precipitator operation.` -r

the A.C.vwave to a precipitator section while the entire section connected Afor energization on the i1* other halfof'the A.C. wave, is disconnected dur-`V vl 'i ing that period. Therefore, both surfaces of the vvcollecting electrodes are inactive atthattime."

In accordance with one formv of` the'invention Ythe other hand, the improved system shown applied alternately to diierent sections of half z This tating elements according to the presenti'nvention do not needto he insulated, this danger is .Y also avoided. -Another advantagek of the lpresent invention is that only a single gap isrequired loen u tween the rotating Yandthe stationary parts of the rectier., v herefore, the voltage and 'power losses in theinultiple gap arrangements of the prior art are avoided.

The :Kspecicnaturef'of the invention, as well f-aswother objects and. advantages thereof, will clearly appear from a description of a preferred embodiment asshown in the accompanying drawings in which:

, Fig. ylshowsa perspective View, partly broken away, 0fl avductmprecipitator employing a par- .;ticular electrode arrangement and energized by one vfor-m ofi mechanical rectifier according Vto the invention5uand Fig.` 2, shows a perspective view, partly broken eaway,- of na diierent electrode arrangement and z c energizedby anotherform of rectifying means according to the invention.

. f The fundamental principleo'f theinvention is 4 described below, opposite surfaces ofthe col'v 1 r shown in l, whereinV source of high volt age current represented by the transformer seca precipitator as' described above, if desired. In

the Asame polarity every ,other `half cycle.' This-fr aids in the removal of the precipitate from the electrodes, since it eliminates all traces of residual ondary2, is connected` lthrough the usual current limiting resistances. i and 5 to terminals 8 and i0, respectively. rerminal 8 is connected to diarnetrically opposed circumferentially, arranged stationary slicesr l2 and i4, while terminal it .is similarly connected to alternatelyvdisposed stationary shoes` Hi and l5. A single uninsfulated rotating arm of conducting material, Zojis' 'driven synchronously -by suitable nslrriaifi A logic-pole motori-,to correspond. to thefstatorshoes so as to successively and alternately provide a low resistance current path to the stator shoes in synchronism with the reversals of alternating current. Rotor arm 2Q is suitably counterbalanced as indicated at 24, so that the system will rotate freely and easily without undue strain on the bearings. Rotating arm 2e is suitably connected to the collector electrodes 25 of a precipitator system, which may be grounded at 28 if desired. Since it is unnecessary to insulate the rotor arm 20 from ground, a conducting bearing with graphite bushing may be employed, or alternatively, a conventional sliding contact, such as a graphite ball in a spring socket, may be employed, the point of Contact coinciding with the center of motor shaft if desired to reduce the relative motion to a minimum. The discharge electrodes 32 in alternate ducts formed by collector plates 26 are connected via high-tension member l0, horizontal conductor 52, vertical conductor 60, bust 53 and lead l2 to terminal l0, while intermediate discharge electrodes 34 are correspondingly connected to terminal 8 via conductor lll. In operation the rotor arm is aligned so that its tip is adjacent to a stator shoe having at that instant the desired polarity, usually positive. There is thus only one active gap in the rectier. Since half the total number of banks of discharge electrodes, in alternate ducts, are connected directly to one end of the high voltage winding, 2, of the transformer, and the other half to the o-ther end of the transformer winding, it will be seen that in operation, full transformer potential exists between the two sets of electrodes, and they are always at opposite polarity, In Fig. l, the upper connection from the transformer end is sho-wn as having instantaneous positive polarity. Through the rotor 2Q the collecting plates are connected to this upper terminal Hl which is thus grounded through the single gap. The discharge electrodes 32, connected solidly to upper terminal ill, are therefore also at positive polarity and grounded in like manner, resulting in like polarity and very nearly equal potential of the discharge wires and the grounded plates in the corresponding ducts so that no electrical action of any kind takes place in the ducts in which discharge electrodes 32 are located. The other banks of discharge electrodes, 34, however, are solidly connected to the lower end 8 of transformer high voltage Wind ing so that they are at this instant energized at negative polarity with the full transformer potential output between them and the sides of the collecting plates facing them. One hundred and eighty degrees later polarity is reversed, but the rotor arm has advanced to the next shoe, again maintaining positive polarity on the plates. Now, the lower end or" the transformer winding 8 is grounded through the gap and with it the banks of discharge electrodes connected to it, while the upper end li] of the winding is negative, as are the discharge electrodes 32 connected to it. Therefore, full potential at correct polarity exists in the adjacent ducts so that each alternate group of ducts is operated half-wave, the precipitator or precipitator section as a whole full wave. With only one gap in the circuit, voltage and power losses are reduced to a minimum. The circuit between discharge electrodes and transformer is never broken so that they remain active to the lowest value at which their charge can maintain a corona current. There is only one gap to give rise to radio or other in terference. The material of the rotor arm is solid metal, eliminating virtually all danger from burning through or failing mechanically and there are no jumper wires, which constitute'probably the major danger of mechanical breakage.

In the alternative form of the rectifier as illustrated in Fig. 2, the counterweight is replaced by a straight line extension 2G of the rotor arm 2B. This provides two rotor arms at 180 mechanical displacement, thus insuring more perfect balance of the rotating elements, but principally placing two gaps in parallel in the circuit and so tending to reduce losses still further. In Fig. 2, a different form of precipitatcr electrode arrangement is shown from that of Fig. l. Casing lili, provided with respective inlet and outlet gas passages 42 and 44, contains two banks of grounded collector electrodes E and e8, which, since they are grounded to the casing, may be mechanically fastened thereto in any suitable manner. Discharge electrode bank 5l! is provided for collector bank 45 and discharge electrode bank 52 is provided for collector bank 53. A housing 5c is provided for an insulator system of which only insulator is shown, which supports horizontal main bus 5S', which in turn supports conducting members 62 by means of vertical conducting members 60, which in turn carry longitudinally extending high-tension members 'Hi'. These high-tension members lil support the longitudinally extending banks of vertical discharge electrodes 5G which may be of conventional type.

Electrodes 52 are supported in identical manner and are electrically connected to conductor l2' which leads to terminal Hl of the rectifier, while discharge electrodes 5u connected through leads 'nl' to terminal 8 of the rectiner. The casing is grounded at 28. It will he apparent that the high-voltage transformer and rectier shoe connections are similar to those shown in Fig. 1.

The operation of the system shown in Fig. 2 is very similar to that shown in Fig. l, except of course that all of the discharge electrodes 56 will be energized simultaneously, while all of electrodes 52 are grounded, and vice versa. An advantage of this arrangement is that during every other half cycle, the opposing electrodes of each group are brought to the same polarity, including both sides of each collector plate electrode 46 or t8 respectviely, which aids in the removal of the precipitate from the electrodes, since no residual charge remains on any of the electrodes #i6 or 48 at this time.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and. arrangements within the scope of my invention as defined in the appended claims.

Iclaim:

l. An electrical precipitator comprising a plurality of parallel collector plate electrodes; discharge electrodes between said plate electrodes, said discharge electrodes being connected to opposite sides of a high-voltage source, a connection from each of said sides to at least one of alternately arranged terminals of a rectifier switch having a movable switch arm electrically connected to a stationary terminal; a connection from said last terminal to said collector plate electrodes; and synchronous driving means operative to successively connect said switch arm to alternate ones of said alternately arranged terminals. v

2. The invention recited in claim 1 wherein said switch arm is a rotating conducting member having conductive bearing means, said stationary terminal being connected to said bearing means.

3. The invention recited in claim 2, said rotating member having two arms extending in opposite directions from said bearing means, a plurality of stationary pole shoes circumierentially arranged in pairs for engagement by said rotating members during rotation thereof, the members of each said pair being electrically connected y and diametrically located for simultaneous respective engagement by said two arms, alternate pairs being connected to opposite sides of said A.C. source.

4. In an electrical precipitator having a plurality of spaced collector electrodes and a p1urality of discharge electrodes intermediate the respective collector electrodes, a charging system comprising a high voltage A.C. source having terminals of opposite polarity, a connection from each of said terminals to certain of said dis charge electrodes, a connection from each of said terminals to at least one of alternately arranged terminals ci a rectifier switch having a movable switch arm electrically connected to a stationary terminal; a connection from said last terminal to said collector electrodes; and synchronous driving means operative to successively connect said switch arm to alternate ones of said alternately arranged terminals.

5. In an electrical precipitator system having a plurality of spaced parallel collector electrodes forming the walls of ducts therebetween and discharge electrodes in said ducts, a charging system comprising a high voltage A.C. source having terminals of opposite polarity, a connection from one of said terminals to the discharge electrodes in certain ones of said ducts, a connection from the other of said terminals to the discharge electrodes in the other ones of said ducts, a connection from each of said terminals to at least one of alternately arranged terminals of a rectifier switch having a movable switch arm electrically connected to a stationary terminal; a connection from said last terminal to said collector electrodes; and synchronous driving means operative to successively connect said switch arm to alternate ones of said alternately arranged terminals.

G. The invention recited in claim 5, said duct means comprising two groups of ducts, the ducts of each respective group being adjacent each other, the discharge electrodes of one group being all connected to the same terminal of the A.C, source and those of the other group being connected to the opposite terminals of the A.C. source.

'7. The invention recited in claim 5, the discharge electrodes of alternating duct means being connected to each other and to respective terminals of the A.C. source.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,000,654 Wintermute f May '7, 1935 FOREIGN PATENTS Number Country Date 541,467 Germany Mar. 26, 1931 

